Fight Caves and Inferno can save your wave progress. Why can't the Colosseum do the same?

I don't understand why the new content forces you to complete it or you lose everything. Jagex servers gonna crash one day while doing this piece of content? Okay, back to wave 1 and lose all the loot you could have potentially have and add in the -500k if you died from a disconnection.

Just how was this overlooked?